If you ever need it you've got an old car like mine. I would vote for the "real" part. That worked great in my situation: My engine light came on after refueling. Not always, but often enough. It usually disappears after a while or after refuelling. This is proof that my old gas cap was not closing properly all along. I bought these, replaced my old one, and a few hours later my engine light went out and hasn't been on since. Definitely solved my problem.
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